Diversity and cover of a sessile animal assemblage does not predict its associated mobile fauna

Abstract

Habitat-forming organisms often determine the structural properties and food resources available to a wide diversity of associated mobile species. Sessile invertebrate assemblages on marine hard substrates support an abundant fauna of mobile invertebrates whose associations with traits of their host assemblages are poorly known. To assess how changes to habitat-forming species are likely to affect their associated mobile fauna, the relationships between abundance, diversity and composition of mobile invertebrates and the diversity, cover and composition of the sessile assemblages they use as habitat were quantified in Sydney Harbour, Australia (33°50′S, 151°16′E). Similar compositions of sessile species were more likely to share a similar composition of mobile species, but univariate measures of the habitat (percent cover, species and functional diversity, prevalence of non-indigenous species) did not predict variation in associated mobile assemblages. These results demonstrate that in this habitat it is difficult to predict the diversity of marine assemblages based on common surrogate measures of biodiversity.

Notes

Acknowledgments

We are grateful to Matthew Pinter, and members of the Subtidal Ecological and Ecotoxicological Research Group—Luke Hedge, Chris Hellyer, Martin Hing, Derrick Cruz, Damon Bolton, Graeme Clark, Louise McKenzie, David Roberts, and Katherine Dafforn—for fieldwork assistance. EMB was supported by the UNSW Evolution and Ecology Research Centre postgraduate scholarship.